At a next step, one calculates \(\Sigma \)  in Eq. (REF ), from which the JIMWLK Hamiltonian is read off as explained above. For massless quarks,
the complete and detailed derivation along this line can be found in Ref. [1]}. Below
we quote the final result for the sake of completeness of our presentation and easy comparison.
In the next section, we will revise the calculation of [1]} by extending it to include finite
quark masses.
